(function (window, document) {
  var hearts = []
  window.requestAnimationFrame = (function () {
    return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame ||
        function (callback) {
          setTimeout(callback, 1000 / 60)
        }
  })()
  init()

  function init() {
    css(".heart{width: 10px;height: 10px;position: fixed;background: #f00;transform: rotate(45deg);-webkit-transform: rotate(45deg);-moz-transform: rotate(45deg);}.heart:after,.heart:before{content: '';width: inherit;height: inherit;background: inherit;border-radius: 50%;-webkit-border-radius: 50%;-moz-border-radius: 50%;position: absolute;}.heart:after{top: -5px;}.heart:before{left: -5px;}")
    attachEvent()
    gameloop()
  }

  function gameloop() {
    for (var i = 0; i < hearts.length; i++) {
      if (hearts[i].alpha <= 0) {
        document.body.removeChild(hearts[i].el)
        hearts.splice(i, 1)
        continue
      }
      hearts[i].y--
      hearts[i].scale += 0.004
      hearts[i].alpha -= 0.013
      hearts[i].el.style.cssText = 'left:' + hearts[i].x + 'px;top:' + hearts[i].y + 'px;opacity:' + hearts[i].alpha + ';transform:scale(' + hearts[i].scale + ',' + hearts[i].scale + ') rotate(45deg);background:' + hearts[i].color
    }
    requestAnimationFrame(gameloop)
  }

  function attachEvent() {
    var old = typeof window.onclick === 'function' && window.onclick
    window.onclick = function (event) {
      old && old()
      createHeart(event)
    }
  }

  function createHeart(event) {
    var d = document.createElement('div')
    d.className = 'heart'
    hearts.push({
      el: d,
      x: event.clientX - 5,
      y: event.clientY - 5,
      scale: 1,
      alpha: 1,
      color: randomColor()
    })
    document.body.appendChild(d)
  }

  function css(css) {
    var style = document.createElement('style')
    style.type = 'text/css'
    try {
      style.appendChild(document.createTextNode(css))
    } catch (ex) {
      style.styleSheet.cssText = css
    }
    document.getElementsByTagName('head')[0].appendChild(style)
  }

  function randomColor() {
    return 'rgb(' + (~~(Math.random() * 255)) + ',' + (~~(Math.random() * 255)) + ',' + (~~(Math.random() * 255)) + ')'
  }
})(window, document)
